Medical laser treatment has been used for several years for various treatments, such as laser surgery, treatment of skin and ulcers or underlying tissue. The effect of the laser therapy is related to the wavelength and the power of the laser light, and it is important that the power of the laser light is controlled within a predetermined range. Also, it is necessary that the power of the laser light emitted does not exceed a certain limit in order to avoid any damages of the treated person.
Therefore, many medical laser apparatuses have been provided with a power stabilizing system for stabilizing the laser light power within a predetermined range.
Prior art laser apparatus for treatment of the skin of a person is usually equipped with a photo diode located in the light emitting diode for absorption of a reflected part of the emitted light during use. Thereby the laser light power is controlled within predetermined limits. However it has been found that some light may be reflected from the skin also, leading to an erroneously high amount of laser energy absorbed by the photo diode because light reflected from the surface to be treated will be absorbed by the photo diode in addition to the light from laser chip. Thereby, the controlling mechanism of the laser apparatus will regulate the light emission to a too low power level. This has in many instances led to a sub-optimal treatment or treatment without any effect, because the laser has almost been shot off during use.